Loss of bottlebrush stiffness due to free polymers

Storm, Ingeborg M.; Kornreich, Micha; Voets, Ilja K.; Beck, Roy; Vries, Renko de; Stuart, MA Martien Cohen; Leermakers, Fam Frans

doi:10.1039/c6sm01227b

Cited by 10 publications

(9 citation statements)

References 52 publications

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“…Inspection of Figure 7 reveals that below the overlap concentration the induced persistence length increases with polymer concentration, whereas above the overlap the induced persistence length drops sharply. This result is comparable to our earlier prediction for chemically grafted bottlebrushes [42]. To explain this drop in induced persistence length, we must realize that in the bottlebrush corona the local polymer density is also in the overlap regime.…”

Section: B Induced Persistence Lengthsupporting

confidence: 89%

Electrostatic stiffening and induced persistence length for coassembled molecular bottlebrushes

et al. 2018

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A self-consistent field analysis for tunable contributions to the persistence length of isolated semiflexible polymer chains including electrostatically driven coassembled deoxyribonucleic acid (DNA) bottlebrushes is presented. When a chain is charged, i.e., for polyelectrolytes, there is, in addition to an intrinsic rigidity, an electrostatic stiffening effect, because the electric double layer resists bending. For molecular bottlebrushes, there is an induced contribution due to the grafts. We explore cases beyond the classical phantom main-chain approximation and elaborate molecularly more realistic models where the backbone has a finite volume, which is necessary for treating coassembled bottlebrushes. We find that the way in which the linear charge density or the grafting density is regulated is important. Typically, the stiffening effect is reduced when there is freedom for these quantities to adapt to the curvature stresses. Electrostatically driven coassembled bottlebrushes, however, are relatively stiff because the chains have a low tendency to escape from the compressed regions and the electrostatic binding force is largest in the convex part. For coassembled bottlebrushes, the induced persistence length is a nonmonotonic function of the polymer concentration: For low polymer concentrations, the stiffening grows quadratically with coverage; for semidilute polymer concentrations, the brush chains retract and regain their Gaussian size. When doing so, they lose their induced persistence length contribution. Our results correlate well with observed physical characteristics of electrostatically driven coassembled DNA-bioengineered protein-polymer bottlebrushes.

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Section: B Induced Persistence Lengthsupporting

confidence: 89%

Electrostatic stiffening and induced persistence length for coassembled molecular bottlebrushes

et al. 2018

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“… 20 The C 4 –B K12 DNA bottle brushes form nematic phases at low weight concentrations, 21 but at high concentrations, excess C 4 -B K12 acts to screen excluded volume interactions, 22 such that the bottle brushes become more flexible and the nematic ordering decreases. 23 …”

Section: Introductionmentioning

confidence: 99%

Force and Scale Dependence of the Elasticity of Self-Assembled DNA Bottle Brushes

et al. 2017

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As a model system to study the elasticity of bottle-brush polymers, we here introduce self-assembled DNA bottle brushes, consisting of a DNA main chain that can be very long and still of precisely defined length, and precisely monodisperse polypeptide side chains that are physically bound to the DNA main chains. Polypeptide side chains have a diblock architecture, where one block is a small archaeal nucleoid protein Sso7d that strongly binds to DNA. The other block is a net neutral, hydrophilic random coil polypeptide with a length of exactly 798 amino acids. Light scattering shows that for saturated brushes the grafting density is one side chain per 5.6 nm of DNA main chain. According to small-angle X-ray scattering, the brush diameter is D = 17 nm. By analyzing configurations of adsorbed DNA bottle brushes using AFM, we find that the effective persistence of the saturated DNA bottle brushes is Peff = 95 nm, but from force–extension curves of single DNA bottle brushes measured using optical tweezers we find Peff = 15 nm. The latter is equal to the value expected for DNA coated by the Sso7d binding block alone. The apparent discrepancy between the two measurements is rationalized in terms of the scale dependence of the bottle-brush elasticity using theory previously developed to analyze the scale-dependent electrostatic stiffening of DNA at low ionic strengths.

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“…Bottlebrush and comb polymers are a class of branched macromolecules consisting of a linear backbone and side chains which alter the intrinsic stiffness of the backbone . The coalescence of a variety of synthetic approaches has resulted in straightforward fabrication of bottlebrushes with wide ranging chemistries and high tunable structures, thereby enabling customization of material properties. − These materials have potential applications in photonics , as pressure sensitive adhesives , and in the biomedical space. , This wide suite of potential applications has prompted a significant interest in understanding the relationship between key molecular parameterssuch as backbone degree of polymerization ( N B ), side chain degree of polymerization ( N S ), and grafting density ( z )and the resulting conformation both in solution and the melt. − In addition to the aforementioned parameters, the conformations of bottlebrush polymers are highly sensitive to concentration. − Previous reports have applied scaling analyses to predict the relationships between structure and conformation as a function of concentration. − In this work, we will use both experiment and simulations to examine the detailed changes in the conformation of a bottlebrush polymer over concentrations spanning the dilute limit to a concentrated solution.…”

Section: Introductionmentioning

confidence: 99%

Concentration Dependence of the Size and Symmetry of a Bottlebrush Polymer in a Good Solvent

et al. 2020

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Bottlebrush polymers consist of a linear backbone with densely grafted side chains which impact the rigidity of the molecule. The persistence length of the bottlebrush backbone in solution is influenced by both the intrinsic structure of the polymer and by the local environment, such as the solvent quality and concentration. Increasing the concentration reduces the overall size of the molecule due to the reduction in backbone stiffness. In this study we map out the size of a bottlebrush polymer as a function of concentration for a single backbone length. Small-angle neutron scattering (SANS) measurements are conducted on a polynorbornene-based bottlebrush with polystyrene side chains in a good solvent. The data are fit using a model which provides both the long and short axis radius of gyration (R g,2 and R g,1 , respectively), providing a measure for how the conformation changes as a function of concentration. At low concentrations a highly anisotropic structure is observed (R g,2 /R g,1 ≈ 4), becoming more isotropic at higher concentrations (R g,2 /R g,1 ≈ 1.5). The concentration scaling for both R g,2 and the overall R g are evaluated and compared with predictions in the literature. Coarse-grained molecular dynamics simulations were also conducted to probe the impact of concentration on bottlebrush conformation showing qualitative agreement with the experimental results.

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Loss of bottlebrush stiffness due to free polymers

Cited by 10 publications

References 52 publications

Electrostatic stiffening and induced persistence length for coassembled molecular bottlebrushes

Electrostatic stiffening and induced persistence length for coassembled molecular bottlebrushes

Force and Scale Dependence of the Elasticity of Self-Assembled DNA Bottle Brushes

Concentration Dependence of the Size and Symmetry of a Bottlebrush Polymer in a Good Solvent

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